甘蔗苗期不同叶位叶绿素荧光特性研究

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摘 要 为明确不同叶位和叶片不同部位叶绿素荧光特性的分布规律及其随生长时间的变化规律，进而实现甘蔗光合潜力的快速评价，本研究通过桶栽试验对3个甘蔗主栽品种（ROC22、ROC16、桂柳05-136）不同叶位和叶片不同部位的叶绿素荧光特性进行比较分析，并研究叶绿素荧光参数对生长时间的响应。结果表明：光系统II（PSII）量子效率（ΦII）随着倒数叶位的增加而下降，在叶片不同部位之间表现为叶中部>叶尖端>叶基部，相同叶位不同品种间ΦII的差异不显著；可调节性能量耗散（ΦNPQ）则随着倒数叶位的增加而上升；非调节性能量耗散（ΦNO）在不同叶位（除倒四叶）及品种间并无显著差异。随着生长时间的推进，上部叶位具有较高的ΦII和较低的ΦNPQ；中部叶位的ΦII和光化学猝灭（qL）变化很小；下部叶位在叶片生长的前两周，能量分配在ΦII和ΦNPQ之间进行，ΦNO基本保持不变；而超过3周后，3个供试品种的ΦII、qL和最大光能利用效率（Fv/Fm）均有不同程度的下降，降幅为ΦII>qL>Fv/Fm，同时伴随着ΦNO的增加。上述结果表明光能利用效率以上部叶位最高，中部叶位稳定，而下部叶位最低且差异较为显著。而不同叶位相对电子传递速率（rETR）对生长时间的响应研究表明，在苗期上部第一片全展叶的中部叶位光能转化能力最强，可选择该叶片的中部叶位进行叶绿素荧光特性横向比较。本研究初步明确了不同叶位光能的利用效率及其随生长时间的变化趋势，为如何选择合适的叶位进行叶绿素荧光检测，进而开展甘蔗冠层光合潜力的快速评价奠定基础。

关键词 甘蔗；叶绿素荧光；叶位；生长时间

中图分类号 S314 文献标识码 A

Abstract To investigate the light excitation energy allocation characters in photosystem II （PSII） of different leaf position and growth time for three tested sugarcane cultivars（ROC22， ROC16 and GUI LIU 05136），several chlorophyll fluorescence parameters were measured and analyzed by using pot experiments. Results showed that， the quantum efficiency of PSII （ΦII） decreased with the leaf counting from the top downward， for different leaf position in three regions of 4 leaves were in order of the middle， the apical， the basal， but there was no significant difference among cultivars. The down-regulated energy dissipation （ΦNPQ） showed an opposite trend compared with ΦII while the non-light induced energy dissipation （ΦNO） remained stable in different cultivars and leaf position. With leaf growth， the upper leaf position showed a relatively high ΦII and low ΦNPQ while the lower leaf position showed a complicate scenario： the light excitation energy distributed between ΦII and ΦNPQ at the first two weeks with stable ΦNO， but over three weeks， ΦII， qL and Fv/Fm declined with different degree（ΦII>qL>Fv/Fm）accompanied the inclined ΦNO， which implied that the middle leaves remained constant， the upper leaves possess the high light use efficiency（LUE） while the lower leaves had low LUE significantly among different leaf position. The analysis of relative electron transport rate（rETR） in different growth time indicated that the middle of the first fully expanded leaf from the top had the maximum rETR in the same period， thus indicating that this leaf could be chosen for chlorophyll fluorescence parameters comparison and evaluation as functional leaf. The results clarified the light use efficiency distributed among canopy， thus could be used in choosing appropriate leaf position for chlorophyll fluorescence diagnosis and set up the basis for the quick evaluation of the photosynthetic potential of sugarcane canopy.